Difference between revisions of "File System"

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(Created page with "CCI is moving to the unified GPFS file system. == General Layout == The Unified CCI GPFS filesystem is built using a block size of 8MiB. Performance testing indicated this was...")
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Revision as of 16:03, 10 January 2014

CCI is moving to the unified GPFS file system.


General Layout

The Unified CCI GPFS filesystem is built using a block size of 8MiB. Performance testing indicated this was about optimal for our storage system hardware. Applications using large-record I/O will benefit most from the large block size. Performance testing shows that applications with small-record I/O perform at least nearly as well with the large block size as in a file system with a much smaller block size.

The file system is broken into three main areas: home, data, and project. Each area of the filesystem has its own purpose and merits.

Tree

/gpfs
 /u
  /home
   /PROJ
    /shared
    /USER
  /data
   /PROJ
    /shared
    /USER
  /project
   /PROJ
    /shared
    /USER

Home (project and per-user)

Home can mean either a project home directory or the associated user home directories. User home directories are only writable by the user while project home directories can be written to by any user within the project. This area of the filesystem has a 10 GB quota and is the only area of the filesystem that uses replication to protect data.

Please note: In GPFS, files are counted twice during quota calculations when they are replicated. This means the home directory limit is effectively 5 GB per project (shared + every user's home).

Data (short-term scratch storage)

There is a data directory for each project and the associated users. as well as corresponding links in each user's home directory. This space is meant as a temporary staging area for performing computation. Performance in this directory will be better than in the home directory!

Important: This space will periodically be purged of files older than 14 days. This policy is subject to change based on filesystem demands. If longer-term storage of data is necessary it should be stored in the project area.

Project (long-term storage)

There is a provisioned directory for each project and the associated users on lb only with corresponding links in each user's home directory. This space is meant to allow for longer-term storage of working data than allowed by the data area. It is not meant for long-term storage of results. This space has a 5G quota and is not replicated.

Additional space may be allocated to a project at the discretion of the CCI Director upon written request by the project PI. Any extended quotas are subject to periodic review and potential reduction at the discretion of the Director.